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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

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Crude paraffin wax is coloured more or less intense yellow or brown,
whilst the refined product is a white or faintly yellow, translucent solid.
The following tests are made :

1.  Suspended Impurities.    Reaction.    Behaviour towards Sul-
phuric Acid.—As with vaseline (q.v., i, 3 and 4).

2.  Melting  and  Solidifying   Points.—The melting point is  deter-
mined as with fats, use being made of a capillary tube blown in the middle
to a bulb and with the lower end bent upwards after the substance has
been introduced (see Fatty Substances, 4).

The solidifying point is determined with the Shukoff apparatus (Fig.
49),x consisting of a wide-mouthed bottle in which is fixed, by means of

a stopper, a tube of the dimensions and form
shown. Through the stopper of this tube there
passes a thermometer reading to 0-1°.

In the inner tube 30-40 grams of the pro-
duct are melted, and when the temperature of
the fused mass is about 5° above the solidify-
ing point, the apparatus is shaken vigorously
and regularly until the contents have become
distinctly turbid and opaque. The shaking
is then discontinued and the thermometer

The solidifying point is taken as the tem-
perature at which the thermometer remains
stationary during the cooling of the fused
paraffin, or as the maximum temperature to
which it rises after a short arrest in the fall.
When no large amount of stearic acid is pre-
sent, only the temperature at which the mer-
cury remains stationary is oboerved.

3. Determination of the Paraffin Wax
(in the crude product).—This is effected by
Holde's method. From 0-5 to i gram of the
substance is dissolved in the necessary quantity

FIG. 49

of ether, an equal volume of absolute alcohol being added and the liquid
cooled to —20°, the subsequent procedure being as described for crude
petroleum (Chemical Tests, 4). The percentage found is increased by i,
to correct for the amount dissolved in the solvents.

With, soft paraffin waxes this method gives less exact although comparative

4. Detection of Resins and Fatty Acids.—Of the presence of admixed

colophony or stearic acid, an indication is obtained from the acid number,

which is zero for pure paraffin wax.    If the product exhibits an acid number,

5-10 grams of it, finely chopped, are digested, with frequent shaking, in the

1 Chem. Zeit., igoi, p. mi.e vaseline should melt to a clear liquid and should not contain mineral